I don’t think Joss would have made Spike a regular and central character, then moved him to Angel after the final season of Buffy, if the actor bringing him to life (so to speak) was difficult, demanding, uncooperative, or unpleasant. So, I assumed James was as professional as he is talented. This interview, along with other references to James’ character (as opposed to Spike’s), extends that image to “really nice guy” - how delightful!